LINE messaging for marketers: A complete guide 

If your customers are in Japan, Thailand, Taiwan, Indonesia, or other parts of Asia-Pacific, there's a good chance the most important messaging app isn't email, SMS, or WhatsApp. It's LINE.

For millions of people, LINE is where they chat with friends, follow brands, receive order updates, book appointments, and interact with businesses every day. In many APAC markets, it isn't simply another messaging channel. It's the default way people communicate, making it an essential part of how businesses build customer relationships.

Now, Customer.io makes it easy to bring LINE into your lifecycle marketing strategy. You can send LINE messages alongside email, SMS, push notifications, and in-app messages as part of the same automated customer journeys, helping you reach customers on the channels they already use. In this guide, we'll explain what LINE messaging is, why it matters, when marketers should use it, and how to start sending LINE messages with Customer.io.

For implementation details, see the Customer.io documentation on sending LINE messages and getting started with LINE.

LINE is a messaging platform that helps businesses communicate with customers through the app they already use to chat with friends, family, and colleagues. Similar to WhatsApp, Messenger, or WeChat, it supports real-time conversations, rich media, images, stickers, and interactive experiences. For businesses, it provides a direct way to deliver updates, promotions, reminders, and customer support through a familiar messaging experience.

What makes LINE unique is its popularity across the Asia-Pacific. While marketers in North America or Europe often think first about email, SMS, or WhatsApp, LINE dominates communication in several of the world's largest markets.

Currently, the platform has more than 90 million monthly active users in Japan and 70-95% market penetration across its core markets, making it one of the most widely used messaging platforms in the region.

That scale has changed how businesses communicate with customers. Instead of treating LINE as another marketing channel, many organizations use it as a primary customer engagement channel alongside email and SMS.

Customers expect to receive order confirmations, appointment reminders, shipping updates, promotional offers, loyalty rewards, and customer support through LINE because it's already part of their daily routine.

For marketers, this presents an important opportunity to engage with customers where they're already at.

LINE isn't growing because it's new. It's growing because it fits naturally into how customers already communicate.

For brands operating in Japan, Thailand, Taiwan, and other parts of Asia-Pacific, LINE offers a familiar, trusted way to reach customers throughout the lifecycle. Instead of relying exclusively on inboxes or text messages, marketers can deliver timely, conversational experiences through a platform customers open throughout the day.

Common use cases include:

• Welcome new customers after they sign up
• Share order confirmations and shipping updates
• Send appointment reminders
• Announce new products or promotions
• Deliver loyalty rewards and exclusive offers
• Encourage customers to return after a period of inactivity
• Provide customer support through two-way conversations

Unlike traditional email campaigns, many of these interactions happen in the same environment customers already use to communicate with the people and businesses they trust. That familiarity makes the experience feel more immediate and personal.

LINE works best when it becomes part of your overall customer communication strategy, not a replacement for the channels you already use.

Like every messaging channel, LINE has strengths. The key is understanding where it creates the most value for your customers.

If someone needs detailed onboarding instructions, email is probably the better choice. If they need an urgent security code, SMS makes sense. But if your audience already uses LINE every day, it's often the most natural place to continue the conversation.

Some of the most effective use cases for LINE messaging include:

The first few interactions set the tone for the customer relationship. Use LINE to welcome new users, introduce your brand, or encourage customers to complete their first key action.

Order confirmations, shipping notifications, appointment reminders, and account updates are all excellent candidates for LINE. Customers expect these messages to be timely, and LINE helps deliver them through a channel they already check regularly.

LINE is well-suited for exclusive offers, seasonal promotions, and loyalty rewards, especially when your audience already follows your brand through an official LINE account.

If customers haven't completed onboarding or haven't tried a key feature, LINE can provide timely reminders or educational messages that help them move forward.

Sometimes customers simply need a reminder to come back. A well-timed LINE message can encourage someone to return to your app, revisit their cart, or continue where they left off.

The common thread isn't the type of message. It's the timing.

The best LINE messages help customers accomplish something they're already trying to do.

Choosing the right channel isn't about deciding which one is "best." It's about choosing the one that's best suited to the moment.

Rather than sending the same message across every channel, consider the customer's experience.

For example, imagine someone purchases a product from your online store.

Instead of receiving the same notification everywhere, their journey might look like this:

• Email confirms the order and includes the receipt.
• LINE shares shipping updates and delivery notifications.
• Push notifications remind them to review their purchase after it arrives.

Each message has a different purpose, but together, they create a connected customer experience.

Adding another messaging channel doesn't automatically improve customer engagement. Like email or SMS, LINE works best when it's used intentionally.

Here are a few best practices to keep in mind.

If your audience actively communicates on LINE, meeting them there creates a more natural customer experience. If they don't, another channel may be a better fit.

Customers typically associate messaging apps with immediate communication. Focus on messages that benefit from being seen quickly, such as order updates, reminders, or time-sensitive offers.

The most effective LINE messages respond to customer actions, not just demographics. Trigger messages based on onboarding progress, purchases, feature adoption, or engagement so every interaction feels relevant.

Sending the same promotion through email, SMS, LINE, and push notifications rarely improves results. Instead, let each channel contribute something unique to the customer journey.

Success isn't determined by how many LINE messages you send. It's determined by whether customers complete the action you intended, whether that's activating an account, completing a purchase, or returning to your product.

Customer.io's native LINE integration lets you add LINE to the same journeys you already build across email, SMS, push notifications, and in-app messaging. Instead of managing another standalone platform, you can orchestrate LINE messages alongside your other channels, giving every customer a more connected experience.

With Customer.io, you can:

• Send text and image messages through LINE.
• Add LINE to automated journeys and one-time campaigns.
• Personalize messages using customer attributes and behavioral data.
• Track message delivery and engagement alongside your other messaging channels.
• Manage LINE messaging from the same workspace where you build the rest of your customer journeys.

To start sending LINE messages, you'll first connect your LINE Official Account to Customer.io, configure your channel settings, and map each customer to their LINE user ID. From there, LINE becomes another available messaging channel inside Journey Builder and Broadcasts. You can follow the complete setup instructions in the Getting started with LINE guide.